Renewed funding is requested for the training grant that supports the Molecular Biophysics Training Program (MBTP) at the University of Wisconsin-Madison. Initiated in 1965 and continuously funded since 1989, the MBTP has served as a nucleus for the Biophysics Graduate Degree Program (BGDP) and a focus for scientific interactions among molecular biophysicists in Chemistry, Biochemistry, and six other departments. In the past five years, ten faculty members with research programs in molecular biophysics have been hired by these departments; they and three UW faculty members with new biophysical research directions have joined the MBTP trainer group. This large-scale expansion in MBTP faculty has been accompanied by corresponding increases in the pool of potential trainees and in the UW-Madison biophysical research infrastructure, including X-ray crystallography, NMR spectroscopy, mass spectrometry and in the Biophysics Instrumentation Facility in Biochemistry. Together these developments demonstrate the success of the MBTP. The MBTP Director is Prof. John Markley, an internationally recognized leader in biological applications of NMR spectroscopy. The Director is assisted in setting program policy and direction by a faculty Advisory Committee consisting of representatives from the major constituent degree programs. Day-to-day administration is by Dr. Kim Voss and staff of the Molecular Virology Institute. Criteria used in the selection of trainees include demonstrated research potential and accomplishment, academic performance, relevance of the student's research project to the program, and recruitment of students from under-represented groups. The MBTP brings students from different backgrounds together, makes available a broad range of research training in molecular biophysics and provides a nucleus for collaborative interactions, while also offering students seminars and courses on systems and methods of molecular biophysics, and providing training in scientific ethics and communication skills. All trainees participate in a weekly literature seminar in biomolecular structure and evening research discussions and mentoring sessions. Many trainees also participate with MBTP faculty in supergroup meetings including Biophysical Chemistry, E. coli Club (RNA polymerase), Metals in Biology, and RNA Maxigroup. New features of the expanded MBTP include an annual poster session and individual advisory committees for each trainee. The success of the program in attracting productive students and the approximately 50% increase in number of faculty trainers in the past five years provides compelling justification for an expansion from the current 10 trainees to a total of 12 trainees with continued support for the next five years.